A. Field of the Invention
This invention relates to the can end manufacturing art, and more particularly to a novel construction and arrangement of press that is used to form a “shell.” The shell is subsequently converted in a separate conversion press into an end for closing off the open end of a can body.
B. Description of Related Art
It is well known to draw and iron a sheet metal blank to make a thin-walled can body for packaging beverages, such as beer, fruit juice or carbonated beverages. In a typical manufacturing method for making a drawn and ironed can body, a circular disk or blank is cut from a sheet of light gauge metal (such as aluminum). The blank is then drawn into a shallow cup using a cup forming punch and die equipment. The cup is then transferred to a body maker or can forming station. The body maker draws and irons the side walls of the cup to approximately the desired height and forms dome or other features on the bottom of the can. After formation of the can by the body maker, the top edge of the can is trimmed. The can is transferred to a necking station, where neck and flange features are formed on the upper region of the can. The flange is used as an attachment feature for permitting the lid for the can, known as an “end” in the art, to be secured to the can.
The end is the subject of a different manufacturing process and involves specially developed machines and systems to manufacture such ends in mass quantities. Representative patents describing end manufacturing methods and presses used to make such ends include Buhrke, U.S. Pat. No. 4,106,422, and Herrmann, U.S. Pat. No. 3,888,199, A press combining formation and shell conversion operations is described in Turner et al., U.S. Pat. No. 6,533,518. After the ends are formed, they are sent to a curling station where a peripheral curl is provided to the end. The peripheral curl is used in a seaming operation to join the can end to the can body. After curling, the ends are sent in stick form to a compound liner station. A water-based compound sealer is applied to the ends in the compound liner station. From there the ends are fed to an inspection station and to a dryer station where the compound is subjected to heated forced air to dry the compound. If a solvent-based compound is used, then no drier is needed. The ends then placed in stick form, bagged, and then loaded on pallets for shipping In the mid-to late 1980's, the art adopted a two-stage type of system for manufacturing can ends. The system uses a shell press that forms shells from a coil of stock material, and one or more end conversion presses that converts the shell into a finished end. A representative prior art shell press and end conversion system is illustrated schematically in FIG. 1. The end manufacturing system 10 of FIG. 1 operates as follows. A coil stock feed mechanism 12 supplies a continuous sheet of end material (e.g., aluminum or steel), to a shell press 14. The shell press 14 has a set of tools that form a shell in the sheet of end material and blanks the shell from the sheet. Shell presses such as shown in FIG. 1 are made by companies such as Formatec Tooling Systems, Inc., Can Industry Products, and Redicon Corp. (now Stolle Machinery, Inc.) and are well known in the art. Representative patents include U.S. Pat. Nos. 4,516,420, 4,587,825, 4,713,958, 4,715,208, 4,716,755, 4,808,052, 4,977,772, 5,626,048, 5,628,224, and 6,658,911, the contents of which are incorporated by reference herein. The shell press 14 in the instant example is a twenty four-out press (i.e., it forms twenty four shells in the sheet of material a direction transverse or oblique to the direction of movement of the sheet in the press). Shells are ejected out both sides of the press 14 and sent to curlers 16, where an edge curl is formed in the periphery of the shell. A representative shell 15 shown in FIG. 1A.
After curling, the shells are placed in stick form and moved along track work indicated at 20 to a balancer 22. The balancer 22 is a robotic distribution machine. It is needed because the curlers 16 are supplying shells along six sets of track work 20, whereas in the downstream direction there are only four sets of track work leading to four liner machines 24. The balancer 22 is used to collect the ends and appropriately distribute them to track work leading to the lining machines 24. The lining machines 24 add a compound liner to the shells. The lining machines supply the shells to a drying machine 26 (if a water-based compound is used), which dries the compound liner with forced air. The drying machine 26 is not needed if a solvent-based compound is used.
The drying machines 26 supply the shells along another set of track work 30 to a second balancer 32. The balancer 32 supplies shells in stick form to three sets of track work 34, 36 and 38 leading to three separate shell conversion presses 40. The conversion presses 40 take the shells of FIG. 1A and complete the formation of the end features in the shell. The conversion presses 40 also have a set of tools that receive a continuous sheet of tab stock from a source 42 and form tabs in the tab stock. The conversion presses 40 attach the tab to the shell, complete the formation of the ends, and supply the finished ends to three sets of track work 43 leading to three bagging stations 44. The converted ends are bagged in stick form and loaded on pallets for distribution to the site where the cans are filled with product.
The conversion presses 40 of FIG. 1 are also known in the art and commercially available from Stolle Machinery Inc., Dayton Reliable Tool & Mfg. Co., and Service Tool Company, among others. They are also described in the patent literature. See U.S. Pat. No. 3,886,881, U.S. Pat. No. 4,723,882; U.S. Pat. No. 4,568,230, and U.S. Pat. No. 4,640,116, the contents of each of which is incorporated by reference herein. The tab presses for forming tabs in the sheet of tab stock are also known and commercially available. See, e.g., the Stolle Conversion System 8 shell conversion press available from Stolle Machinery Inc., and the above referenced '230 patent. The details of the work stations and forming operations performed on the shell in a conversion press 40 will depend on the type of end and the requirements of the customer.
The present invention relates to an improved shell press 14 that forms shells out of flat stock fed into the press. The shell press of this invention can be used in the system of FIG. 1 for the shell press 14. Shell presses known in the art generally fall into one of two categories: single action and double action presses. Single action presses use a single driving mechanism (ram device) to move the upper tool. Double action presses use two driving rams, an inner ram and an outer ram. Double action presses are shown for example in U.S. Pat. Nos. 4,713,958 and 4,977,772, assigned on its face to Redicon, and U.S. Pat. No. 5,626,048, assigned on its face to Can Industry Products. Double action presses are considerably more complex and costly machines and are more expensive to maintain and operate. The features of this invention allow for a single action press to be used to make shells, and thus presents a potential for significant cost savings for can end manufacturers.